Device for relative displacement of two elements

ABSTRACT

A device for relative movement of two elements ( 1, 2 ) comprises two link arrangement ( 5, 6 ) coupled in series by means of a connection arrangement ( 4 ). A first link arrangement ( 5 ) comprises at least three links ( 9, 14 ), which have substantially equal length and which are substantially parallel, said links ( 9, 14 ) being oriented in a substantially triangular relation, viewed along the longitudinal direction of the links, between the connection arrangement ( 4 ) and the element ( 2 ). The second link arrangement ( 6 ) comprises at least one parallelogram acting between the connection arrangement ( 4 ) and the element ( 1 ). First the second force-applying arrangements ( 17, 18 ) are adapted to cause the first link arrangement ( 5 ) to pivot. A third force-applying arrangement ( 33 ) is adapted to cause the second link arrangement ( 6 ) to pivot.

FIELD OF THE INVENTION

This invention is related to a device for relative movement of twoelements comprising an arrangement for forming a connection between afirst link arrangement and a movement arrangement, the movementarrangement being provided between the connection arrangement and one ofthe elements whereas the first link arrangement is provided between theconnection arrangement and a second of the elements.

The relative movement of the two elements has the purpose to positionthem mutually in a manner aimed at by means of the force-applyingarrangements. More specifically, the device according to the inventionis intended to form a manipulator or robot. The second of the elementsis intended to carry, directly or indirectly via a carrying arrangement,or constitute a working member to execute the function aimed at, forinstance picking, placing, packing and palletising. However, it isremarked that the working member may be adapted to carry out also otherwork operations than those just mentioned. The first element mayaccording to a first embodiment form a base member secured in space butcould according to a second embodiment form at least a part of a carriermovable relative to a base member. A force-applying arrangement thenserves for adjusting the position of the carrier relative to the basemember.

PRIOR ART

A robot of the kind defined by way of introduction is described in U.S.Pat. No. 4,976,582. For the positioning of the second element, the robotcomprises three force-applying arrangements, which in unison comprisethree force-exerting members arranged in a triangular distribution onthe first element. Each of the force members is connected to the movablesecond element via its own connection comprising two link arrangementsand an intermediate connection arrangement. These three connectionscoupled in parallel are like-wise arranged in a triangular distribution.Each of these connections comprises a first link arrangement includingtwo first links pivotably connected to the second element and a secondlink, which is rigidly connected to a movable portion of theforce-exerting member and which by means of a connection arrangement isconnected to the two first links. The second link is movable with regardto one single degree of freedom relative to the stationary portion ofthe power-exerting member. The connection arrangement connects the firstand second links in a hinged manner with two but not more than twodegrees of freedom. The link arrangement formed by the first links isconnected to the second element so that two but not more than twodegrees of freedom occur. In reality, the first link arrangements formparallelogram-shaped four-links systems. A disadvantage with this knowntype of robot is that it becomes comparatively bulky as a consequence ofthe triangular distribution discussed herein above. The angle betweenplanes of pivoting of two adjacent second links must, namely, always beless than 180°. Thus, it is very difficult to arrange two or more ofthose robots closely to each other without collision. A furtherdisadvantage is that it is structurally difficult to design the knownrobot with the required stiffness and strength since the movableportions of the three power-exerting members project in a star-likefashion from the first element, which with regard to the spacerequirement should be formed as small as possible but which on the otherhand must be able to receive the power-exerting members. Thus, thismeans that it becomes difficult to design arms rigidly connected to themovable portions of the power-exerting members with a sufficient widthas far as the arms themselves are concerned as well as their bearings atthe first element.

A further disadvantage is that all arm lengths must be equal. This meansthat it is not possible to optimize the robot to the pattern of movementin question. Performance will always be symmetrically distributed in asymmetrical working area, which is not cost efficient.

Furthermore, the known robot cannot execute a tilt movement of thesecond element to fetch objects located sidewardly of or above therobot.

In addition, 3 further motors are required in order to change theinclination of the second element. It would be desirable to manage thiswill only 1 extra motor in order to achieve a cost-efficient concept.

As a consequence of the equilateral triangular construction of the knownrobot it is also difficult to arrange to work horizontally aboveconveyors, loading pallets etc. Furthermore, it should be mentioned thatif a working member on the second element is to be driven by means of amotor on the first element, an axle extending between the first andsecond elements must comprises a torque-transmitting coupling allowingvariation of the length of the axle. In practice, the axle is suitablydesigned as consisting of two axle parts, which are displacabletelescopically relative to each other and the torque transmission ofwhich is ensured by splines, wedge grooves or similar. This complicatesthe embodiment and makes the same more costly.

OBJECT OF THE INVENTION

This invention aims at devising routes to develop the device of the kinddefined by way of introduction so as to eliminate or at least reduce oneor more of the disadvantages mentioned herein above. According to a subaspect, the aim is to provide a greater flexibility as to the design ofthe device so that two or more devices may be placed to workcomparatively close to each other. According to another sub aspect, animproved mobility of the robot is aimed at.

SUMMARY OF THE INVENTION

The object of the invention is achieved in that the first linkarrangement comprises links pivotably connected relative to theconnection arrangement and the associated of the elements via joints,that the movement arrangement is adapted to allow a relative movementbetween the connection arrangement and the associated of the elements,and that the device comprises force-applying arrangements to actuate thelink arrangement and the movement arrangement so as to change therelative position between the elements.

Thus, the link arrangement forms an interconnection between theconnection arrangement and the associated of the elements by means of atleast two and preferably three links. This creates possibilities for anasymmetrical design of the device according to the invention and,accordingly, an adjustment of the working area thereof to its purpose.For instance, this asymmetrical character of the device according to theinvention provides possibilities for a very dense packing of a pluralityof robots. This differentiates the device according to the inventionfrom the device according to U.S. Pat. No. 4,976,582, where a triangularstructure with equal sides is aimed at and where in any case the anglebetween the planes of pivoting of two adjacent second links always mustbe less than 180°.

It is according to an embodiment possible to design the displacementarrangement as a second four-links system. In such cases the first andsecond four-links systems will, accordingly, be coupled in series toeach other via the connection arrangement. This provides the device withvery favourable operational qualities. A particularly advantageousoption resides in the second four-links system being possible to use forachieving tilting of the working member by means of a force-applyingarrangement comprising one single force-exerting member.

The use of two four-links systems coupled in series via the connectionarrangement involves, in addition, in case the four-links systems aredesigned as parallelograms, that it is made possible to achieve forcetransmission via axles provided in the four-links systems and withassistance of cardan joints, angular gears and the like without havingto introduce, in the axle sequence, any sliding couplings or similarintended to operate axle length compensating.

According to a preferable embodiment of the invention, the movementarrangement is designed as a pivot arm.

Several preferable developments of the invention are defined in thedependent claims. These developments and advantages in connection withthe invention are dealt with more specifically in the followingdescription.

SHORT DESCRIPTION OF THE DRAWINGS

With reference to the enclosed drawings, a more close description ofembodiment examples of the invention follows hereunder:

In the drawings;

FIG. 1 is a side view of the robot according to the invention in adiagrammatical form;

FIG. 2 is a, still, diagrammatical view of the robot in perspective;

FIGS. 3 and 4 are views similar to FIG. 1 of the robot in differentpositions;

FIG. 5 is a diagrammatical and perspective view illustrating atransmission for incorporation into a robot of the basic structureappearing from FIGS. 1-4;

FIG. 6 is a detailed view illustrating an alternative embodiment of thefirst link arrangement;

FIG. 7 is a perspective view of a robot, which in its basic featurescorresponds to the one illustrated in FIGS. 1-4 but having itsfour-links system formulated in a different manner;

FIG. 8 is a partly cut perspective view of a detail appearing from FIG.7;

FIG. 9 is a perspective view of an alternative robot design;

FIG. 10 is a perspective view of a further alternative;

FIG. 11 is a further perspective view of a robot alternative;

FIG. 12 is a perspective view of a further robot design;

FIG. 13 is a view similar to FIG. 12 but illustrating the robot in adifferent position;

FIG. 14 is a perspective view illustrating a driving device intended foruse in a robot of the basic type according to e.g. FIGS. 12-13;

FIG. 15 is a diagrammatical and perspective view illustrating how thedouble power transmission may be realised in a joint having two degreesof freedom, more specifically freedom to pivot about two axes extendingat an angle relative to each other; and

FIG. 16 is a perspective view similar to the one in FIG. 14 butillustrating a somewhat modified embodiment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In order to simplify the understanding, like reference characters havebeen used in the following in different embodiments for similar orcorresponding components but with addition of letters specific toembodiments.

The robot illustrated in FIGS. 1-4 is intended for relative displacementof two elements 1, 2. The element 1 is in this example intended to forma base member, relative to which the element 2 is intended to bepositioned in space. The element 2 is intended to carry, either directlyas indicated in FIG. 1, or, as will be dealt with later, indirectly viaa carrying arrangement, a working member 3.

The robot comprises an arrangement 4 for forming a connection between alink arrangement 5 and a movement arrangement 6. The link arrangement 5is provided between the connection arrangement 4 and the second element2 whereas the movement arrangement 6 is provided between the connectionarrangement 4 and first element 1. The link arrangement 5 comprises atleast two first links 9 pivotably connected relative to the connectionarrangement 4 and the element 2 via joints 7 and 8 respectively, saidfirst links forming, together with the connection arrangement 4 and theelement 2, a first four-links system FS1. The joints 7, 8 of each ofthose links 9 are designed such that the link in question becomespivotable in all directions relative to both the connection arrangement4 and the element 2.

The movement arrangement 6 is adapted to allow relative movement betweenthe connection arrangement 4 and the first element 1. More specifically,the movement arrangement 6 is intended to be used for movement of theconnection arrangement 4 relative to element 1. It is then preferredthat the movement arrangement 6 is adapted to maintain, on such relativedisplacement between the element 1 and connection arrangement 4, asubstantially constant relation between themselves as far as inclinationis concerned. Expressed in other words, the connection arrangement 4 isintended to be moved, on operation of the movement arrangement 6,relative to the element 1 without changing the orientation of theconnection arrangement 4 in space. As an example of movementarrangements 6, those capable of achieving linear movements, forinstance piston cylinder mechanisms, ball screw arrangements and rackdriving devices may be mentioned. By such linear displacement theconstant orientation of the connection arrangement 4 is ensured.However, it is pointed out that also types of movement arrangements maybe in question.

According to a particularly preferred embodiment of the invention, themovement arrangement 6 is designed as a second link arrangementcomprising at least one second link 10 pivotable relative to theconnection arrangement 4 and the first element 1. It is thenparticularly preferred that the link arrangement 6 comprises at leasttwo second links 10, 11 pivotable relative to the connection arrangement4 and the first element 1. The link arrangement 6 forms with its link10, 11 and together with the connection arrangement 4 and the element 1a second four-links system FS2. The joints of the links 10, 11 relativeto element 1 are denoted 12 whereas the joints relative to theconnection arrangement 4 are denoted 13 (see FIG. 1).

It is preferred that the joints 12, 13 in the four-links system FS2allow one single degree of freedom, i.e. a pure pivoting movement aboutpivoting axes parallel to each other. Thus, the four-links system FS2will pivot in parallel planes.

The link arrangement 5 comprises at least one third link 14 pivotablyconnected relative to the connection arrangement 4 and the element 2 viajoints 15 and 16 respectively. The joints 7, 15; 8, 16 of the first andthird links 9, 14 are disposed in a triangular configuration. Aright-angled triangular configuration is illustrated in FIGS. 1-4 butthe angles thereof could also be smaller or larger than a right angle.The minimum criterium in this respect is that the joints form saidtriangular configuration, i.e. that the joints are not located in oneand the same plane. The triangular configuration means that the links 9,14 will carry the element 2 in at least three points.

The link 14 forms with each of the links 9, the connection arrangement 4and the element 2 a third four-links system FS3. Accordingly, twofour-links systems FS3 are involved in the example. It is pointed outthat of course more than one link 14 may occur. More four-links systemsFS3 are then of course formed. Besides, more than two links 9 may occurso that, accordingly, more four-links systems FS1 are formed. The links9 are substantially equal in length. In addition, they are substantiallyparallel. Thus, the four-links system FS1 forms a parallelogram.

The links 10, 11 are substantially equal in length. They are alsopreferably substantially parallel. Thus, also the four-links system FS2forms a parallelogram.

The link 14 is substantially equal in length to the links 9. Besides,the link 14 is preferably substantially parallel to the links 9. Each ofthe two four-links systems FS3 occurring in the example forms,accordingly, parallelograms. It is pointed out that in case severallinks 14 occur, they should be substantially equal in length to thelinks 9 and substantially parallel thereto. It is pointed out that thelink arrangements 5 and 6 in the example are connected by means of theconnection arrangement 4 such that an angle α, more specifically, asubstantially right angle, is present between a plane P1 through thejoints 7 and 15 and a plane P2 (see FIG. 3) intersecting the joints 13and extending perpendicularly to the plane of pivoting of the links 10,11. As will appear in the following, said angle may, however, bearbitrary within the internal 0-360°. In the embodiment illustrated andhaving an angle of about 90°, the connection arrangement 4 will, viewedfrom the side according to FIGS. 1 and 3-4, comprise a substantiallyL-like shape. In the orientation according to the figures the connectionarrangement 4 comprises, viewed from the side, a substantially verticalshank and a substantially horizontal shank. The vertical shank iscoupled to the links 10, 11 whereas the horizontal is coupled to thelinks 9 and 14. The horizontal shank may have, as viewed from above, anangle shape with two legs, one of which extends along FS1 whereas theother extends along one of FS3.

The links 9, 14 of the first link arrangement 5 and the joints 7, 8 and15, 16 respectively belonging thereto form in this case between theconnection arrangement 4 and the second element 2 connections, which allallow relative rotation about axes substantially parallel to the links.Such an embodiment presupposes that the links 7, 8, 15, 16 give threedegrees of freedom, namely the previously discussed pivoting about tworeal or virtual axes at an angle to each other plus said rotation aboutaxes parallel to the links 9, 14. Such a design has the advantage thatthe links 9, 14 and their joints do not have to be dimensioned in orderto adopt rotational strains. An example of design of the joints for thispurpose is as ball joints. However, it is pointed out that the minimumcriterion for functionality according to the invention as far as thejoints 7, 8 and 15, 16 are concerned is that they should provide freedomfor the links 9, 14 to pivot in all directions in relation to theconnection arrangement 4 and the second element 2, i.e. that two degreesof freedom in the form of pivoting about two axes forming an anglebetween themselves must occur. When not more than two degrees of freedomin this way are present, the links and their joints are capable oftransferring rotational strains about axes parallel to the links. Insuch a case the joints could consist of cardan joints or other jointshaving double, non-parallel pivot axes.

First 17 and second 18 force-applying arrangement are adapted to causethe links 9, 14 in the link arrangement 5 to pivot relative to theconnection arrangement 4. The arrangements 17, 18 comprise each apower-exerting member 19 and 20 respectively having a stationary portionrigidly connected relative to the element 1 and a movable portion 21 and22 respectively having one single degree of freedom relative to thestationary portion and being connection to the element 2 via arespective link arm arrangement 23, 24. The force-applying arrangements17, 18 are adapted to actuate the element 2 in mutually differentdirections to adjust the same in space.

The link arm arrangement 23 in one of the force-applying arrangements,namely the one denoted 17, comprises at least two link arms 26, whichare hingedly connected to the element 2 via joints 27 and to the movableportion 21 via joints 29. Each of these joints 27, 29 should be designedso as to allow pivoting of the individual link arm 26 in all directionsrelative to the second element 2 and movable portion 21, i.e. that atleast two degrees of freedom should be present, namely possibility forpivoting about double, non-parallel pivoting axes. The joints may, thus,in this case consist of cardan joints or other two axes joints. Inaddition, it is included within the scope of the invention that each ofthe joints 27, 29 may comprise a further degree of freedom relative tothe element 2 or the movable portion 21, namely rotation about an axissubstantially parallel to the link arm 26 in question. In such a casethe joints may for instance be formed by ball joints.

The link arm arrangement 23 comprises in the example a third link arm28, which is connected to the link arms 26 via the joints 29. On theother hand, the link arm 28 is rigidly connected to the movable portion21 or alternatively connected to the portion 21 via a joint 30comprising one single degree of freedom, i.e. in practice pure rotation.

The link arms 26 form, together with the associated joints 27, 29, afour-links system. It is preferred that this system is designed as aparallelogram.

Since the movable portion 21 presents only one degree of freedomrelative to element 1, the link arm 28 will maintain its orientation inspace. The parallelogram structure formed by said link arm and the linkarms 26 in combination with the element 2 involves, accordingly, thatthe force-applying arrangement 23 in its entirety will lock the secondelement 2 against pivoting relative to the connection arrangement 4about axes substantially perpendicular to planes, in which joints 7, 15;8, 16 present at the ends of the links 9, 14 reside. This characteristicof the link arm arrangement 23 involves, accordingly, that the element 2will be locked in space, provided that FS2 is lockable, as far alldegrees of freedom are concerned, except for one further, whichaccordingly must be provided by the second force-applying arrangement18.

The only remaining degree of freedom may be locked in case the link armarrangement 24 comprises one single link arm 31, which is connected tothe movable portion 22 and the second element 2 via joints 32. Thesejoints should be designed so that the link arm 31 is pivotable in alldirections relative to the movable portion 22 as well as to element 2.In addition, the joint 32 could allow one further degree of freedom inthe form of rotation about an axis parallel to the link arm 31 relativeto the movable portion 22 and the element 2. In the latter case, threedegrees of freedom would be at hand. Thus, the joints 32 could consistof cardan joints, other joints allowing pivoting about double,non-parallel axes, universal joints, ball joints etc. An alternative todesign of the link arm arrangement 24 as consisting of one single linkarm 31 is to design the same analogous to the link arm arrangement 23.This is not necessary in order to achieve locking of all degrees offreedom but may be desirable in certain cases due to the extra stabilityachieved with double link arms.

It is pointed out that hereinafter joints allowing one single degree offreedom at times will be indicated by means of an oval (see the joint30) in perspective views whereas joints with two more degrees of freedomare indicated with a circle.

The power-exerting member 19 and/or 20 is, in the example, formed by arotary means, the stator of which forms the stationary portion and therotor of which forms or is included in the movable portion 21 and 22respectively. In the example the movable portion 21, 22 has thecharacter of an arm pivotable with one degree of freedom. However, it ispointed out that the movable portion 21 and 22 respectively also couldbe movable as far as one single other degree of freedom is concerned,for instance translation. Such portion 21, 22 movable in translationwould then in an analogous manner be connected, by means of its extremeend, to the link arm arrangement 23 and 24 respectively.

A third force-applying arrangement 33 is adapted to cause the secondlinks 10, 11 to pivot relative to the element 1. The arrangement 33comprises a power-exerting member having a stationary portion rigidlyconnected relative to the first element 1 and a movable portion which isconnected to one of the links, namely the one denoted 10. Thepower-exerting member 33 is suitably formed by a rotary means, thestator of which forms the stationary portion and the rotor of which isrigidly connected to the link 10.

As far as the robot has been described until now and based on FIG. 1,pivoting of the links 10, 11 by means of the force member 33 causes theconnection arrangement 4 to be moved in space in a parallel manner whilemaintaining its orientation and the corresponding is relevant as to theelement 2 by intermediary of the link arrangement 5.

However, the robot comprises a design, by means of which the element 2may be changed as far as its orientation is concerned, i.e. titled, andthis more specifically as a consequence of a change of form of the linkarrangement 6. For this purpose the first element 1 is formed by twoparts 1A and 1B, which are hingedly connected to each other about anaxis coinciding with the hinge axis 12 of the link 10. A fourthforce-applying arrangement 34 is adapted to pivot the second part 1Brelative to a first 1A of the parts. This second part 1B forms a link inthe four-links system FS2 in that it is hingedly connected to the twolink 11. The arrangement 34 comprises a power-exerting member having astationary portion rigidly connected to the element part 1A and amovable portion rigidly connected to the part 1B. More specifically, thepower member 34 is formed by a rotary means, the stator being connectedto the part 1A and the rotor of which is connected to the part 1B.

When the force member 33 is immobilized, the link 10 assumes one and thesame position in space. When the force member 34 is driven, thepart/link 1B will be pivoted in space and then also relative to the link10. This gives rise to a deformation of the parallelogram FS2 such thatthe connection arrangement 4 and, accordingly, also the element 2 willbe inclined as appears from FIGS. 3 and 4. Such inclination involves afurther degree of freedom for a working member provided on the element2. When the force member 34 is immobilised, the link/part 1B assumes,always, one and the same position relative to the part 1A, which meansthat then no tilting of the element 2 may occur but instead pivoting ofthe link 10 involves movement in the space of element 2 whilemaintaining a constant orientation.

It appears from FIG. 2 that the element 2 may be moved in the plane XYby pivoting of the links 9, 14 may means of the force-applyingarrangements 17, 18. By pivoting the links 10, 11 the element 2 may bedisplaced in the XZ-plane.

However, it is pointed out that it is well within the scope of theinvention that the parallelogram FS2 works more or less obliquelyrelative to the XZ-plane.

The transmission 80 illustrated in FIG. 5 is adapted to transmit drivingforce, in a robot of the basic type illustrated in FIGS. 1-4, from aforce-exerting arrangement 81 provided on the first element 1 o to theworking member 3 o in order to turn the same relative to the secondelement 2 o. The four-links system FS2 is illustrated in FIG. 5 but notthe link arrangement 5 and neither any connection arrangement 4 formutually connecting the four-links system FS2 and the link arrangement.The force member 33 o intended for pivoting the link 10 o is, however,illustrated in FIG. 5.

The transmission 80 comprises first force transmitting members extendingalong the four-links system FS2. More specifically, these forcetransmitting members comprise a traction force transmitting element 82laid around diverting wheels 83, 84. These diverting wheels 83, 84 havetheir axes of rotation coinciding with joints 12 o and 13 o in thefour-links system FS2. The force member 81 in the form of a rotary motorhas its stator fixed to the first element 1 o and its rotor drivinglyconnected to the diverting wheel 83. The second diverting wheel 84 isdrivingly connected to an axle 85, which carries a gear wheel 86, whichin connection with a further gear wheel 87, forms an angular gear.

A link 88 is diagrammatically illustrated in FIG. 5. This link may beformed by some of the links comprised in the first link arrangement 5(compare with FIGS. 1-4) but could also consist of a further linkarranged in a parallel relation to the links in the link arrangement 5.Independently of the individual case, the gear wheel 87 is connected toan axle 89, on which a further diverting wheel 90 is placed. Around thisdiverting wheel 90 and a diverting wheel 91 arranged at the opposite endof the link 88, a second traction force transmitting element 92 is laid.The diverting wheel 91 is arranged on an axle 93, on which also a bevelgear wheel 94 is arranged. This gear wheel 94 is in engagement with afurther bevel gear wheel 95, the axis of rotation of which isperpendicular to the axle 93. This gear wheel 95 is in its turn inangular engagement with a further gear wheel 96, the axis of rotation ofwhich is perpendicular to the axis of rotation of the gear wheel 95.Thus, the gear wheel 95 has teeth shaped such, suitably on both sides,that it may be in engagement with both gear wheels 94 and 96. Theworking member 3 o is in the example connected to the gear wheel 96 viathe common axle 97 so as to be secured against rotation relative to thegear wheel 96. The gear wheel 95 and its axle is rotatably journalled ona part comprised in the second element 2 o as indicated in FIG. 5.

The angular gears described and formed by means of the gear wheels 86,87 and 94 and 95 respectively form joints allowing the desiredadjustment of the four-links system FS2 and also the four-links systemsFS1 and FS3 contained in the link arrangement 5 without the forcetransmission illustrated in FIG. 5 involving any limitation on the fullmobility of the four-links systems.

A somewhat modified design of the link arrangement 5 p is illustrated inFIG. 6. The link arrangement 5 p forms, still, the four-links systemsFS1 and FS3 in a manner previously described with assistance of FIGS.1-4. However, the difference is that the four-links system FS1 is formedby two traction force transmitting, but not compression-forcetransmitting, first links 9 pA and, besides, a further first link 9 pE,which, however, is compression-force transmitting, i.e. defines thedistance. It should be pointed out already now that the links 9 p, 14 pof the first link arrangement 5 p and the joints associated thereto formconnections between the connection arrangement 4 p and the secondelement 2 p, at least one of these connections being rigid againstrotation, i.e. capable of transferring torque about an axis parallel tothe connection. In the example, both links 9 p and 14 p form suchconnections rigid to rotation.

The first links 9 pA and 9 pB are formed by traction force transmittingelements arranged to maintain the orientation in space of the associatedsecond element 9 p on movement of the link arrangement 5 p. The twotraction force transmitting elements form parts of a loop laid arounddiverting members 98, 99 connected to the connection arrangement 4 p andthe second element 2 p respectively. The loop is secured againstdisplacement relative to the diverting members 98, 99. The latter onesform substantially arc-shaped diverting paths for the parts of the loop.At a suitable place along these diverting paths, the loop is securedrelative to the diverting members 98, 99 by means of suitable securingelements. In the example it appears that the diverting members 98, 99are formed by wheels having a peripherical groove, in which the loop isreceived. These wheels are connected to connecting parts 43 so as to besecured against relative rotation thereto, said connection parts 43being hingedly connected to the connection arrangement 4 p and thesecond element 2 p respectively about axles 74. The first link 9 pBcapable of compression-force transmission has its end portions hingedlyconnected to the connection parts 43, and more specifically such thatthe hinge axles 7 p are concentrical to the axes of the divertingmembers 98, 99.

In other words, the first link 9 pB is pivotably about its joints 7 p inplanes parallel to the joint axles 74 connecting the connection parts 43and the connection arrangement 4 p and the second element 2 prespectively. Thus, this means that the links 9 pA and 9 pB may bedescribed as being connected to the connection arrangement 4 p and thesecond element 2 p so as to be pivotable in all directions. In suchpivoting about the joint axles 7 p, the traction force transmittingelements or links 9 pA will, at different places along the periphery ofthe diverting members 98, 99, exit and enter respectively theperipherical grooves of the diverting members while executing a parallelcontrolling function between the connection arrangement 4 p and thesecond element 2 p.

As far as the link 14 p is concerned, it may be established that itforms third four-links systems FS3 with each of the links 9 pA and 9 pB.Also the link 14 p may be carried out with diverting members accordingto 9 pA, 9 pB, 7 p, 47.

It is illustrated in FIGS. 7 and 8 how a robot similar to the onediscussed in FIGS. 1-4 may be achieved by means of parallel controllinglink systems of the kind described with assistance of FIG. 6, and morespecifically such that these parallel controlling link systemsconsisting of diverting members, traction force transmitting elementloops and central further links form the various four-links systems FS1,FS2 and FS3, the parallel link system 26 in addition being provided withsuch a parallel controlling link system as described with the assistanceof FIG. 6.

Under normal conditions, it is preferable to form the four-links systemsFS1, FS2 and FS3 with their links in the manner described with theresistance of FIGS. 1-4 by designs such as those illustrated in FIGS.6-8 are functionally equivalent and are included within the scope of theinvention as far as the actual definitions of the links 9, 14; 10, 11and the four-links systems formed thereby are concerned. FIG. 9illustrates a robot variant corresponding to the one described withassistance of FIGS. 1-4 as far as the link arrangement 5 q and theforce-applying first and second arrangements 17 q and 18 q areconcerned. The difference consists in the movement arrangement 6 q herenot being designed as four-links system FS2 but instead as a pivot arm100 pivotably arranged relative to the first element 1 q, which isshaped as a base member, about an axis 101. This pivot arm 100 will atthe same time fulfil the function of the connection arrangement 4 in thepreviously described embodiment since the first and third links 9 q, 14q are connected to the pivot arm 100 via joints. It is in thisconnection pointed out that the length of the pivot arm 100 illustratedin FIG. 9 may be adjusted to the desired working area of the robot. Theforce-exerting arrangement 33 q executing pivoting of the pivot arm 100about the axis 100 comprises a force-exerting member, the stator ofwhich is connected to the first element 1 q whereas the rotor thereof isconnected to the pivot arm 100. Besides, it is pointed out that theforce-exerting member 19 q comprised in the force-applying arrangement17 q is also connected to the rotor of the force-exerting member 33 q soas to accompany the rotor in its rotation. The force-exerting member 19q has its weight centered relative to the pivot axis 101 so as tominimize inertia occurring on pivoting of the pivot arm 100.

In the example the pivot arm 100 is illustrated as orientatedsubstantially perpendicularly to the pivot axis 101. This is, however,not a necessity.

It is preferable, although not necessary, that the axis of theforce-exerting member 20 q is co-axial to the axis of the force-exertingmember 33 q.

It is pointed out that since the movement arrangement, which correspondsto the one denoted 6 in FIGS. 1-4 and which is formed as a pivot arm100, will carry out a pivoting movement about the axis 101 and theworking member 3 q as a consequence thereof will be pivoted dependingupon the pivoting movement, compensating turning of the working member 3q is, depending on the circumstances, necessary to avoid the pivotingmovement of the pivot arm 100 to locate the working member 3 q inorientations (rotational positions) which are not desired. Thus, a pivotarm embodiment of the movement arrangement 6 according to FIGS. 1-4 isnormally only cost efficient when an operating device for turning theworking member 3 q relative to the second element 2 q is required forother reasons. This disadvantage is in applications compensated by thefact that the pivot arm solution enables the entire robot to be pivotedaround in a large angle (up to 360°) and in certain embodiments morethan one revolution (even several revolutions), which gives a largeworking area and a possibility to always resort to the most direct routeindependently of on which revolution the pivot arm is present.

The variant of the embodiment in FIG. 9 illustrated in FIG. 10 involvesdifferences a.o. as far as the design of the driving arrangement isconcerned. As before, the device comprises first and secondforce-applying arrangements 17 r, 18 r for causing the second element 2r to move relative to the pivot arm 100 r (movement arrangement 6 r).The third force-applying arrangement 33 r serves for pivoting the pivotarm 100 r relative to the first element 1 r. These differentforce-applying arrangements comprise force-exerting members 19 r, 20 rand 33 r respectively consisting of drive means with stators and rotors.The drive means 19 r, 20 r and 33 r have their stators secured relativeto the first element 1 r, i.e. in the example some kind of base, whichin itself may be mobile. The rotors of the rotary means are arrangedwith their axes of rotation substantially parallel and preferablycoinciding, as is indicated in FIG. 10, with the axis 101.

The rotor of the rotary means 19 r is adapted to actuate, via an angularrear 112, 113, the second element 2 r via the link arm arrangement 17 r.A first gear wheel 112 included in the angular gear is secured to therotor of the rotary means 19 r whereas a second gear wheel 113 includedin the angular gear is rotatably supported by a carrier 110, which isadapted to be put into a rotational movement on pivoting of the pivotarm 100 r by means of the rotary means 33 r. In other words, the rotorof the rotary means 33 r is connected to the carrier 110 so as to besecured against relative rotation thereto. The axis of rotation of thegear wheel 113 is denoted 111.

A link arm 148 comprised in the link arm arrangement 17 r is rigidlyconnected to the gear wheel 113 to be put in a pivoting motion onrotation of the gear wheel.

The embodiment described according to FIG. 10 has the advantage that thestators of the rotary means do not have to be put in movement when thedevice is to be moved but it is only the rotors of the rotary means thatexecute what is required. This gives rise to an embodiment having aminimum of mass inertia. It is pointed out that the carrier 110 and theangular gear 112, 113 may be realised with substantially less mass thanthe stator of a rotary means. In the embodiment according to FIG. 9,there is the disadvantage that the entire rotary means 19 q must be putin rotation by means of the rotary means 33 q.

In addition, the variant illustrated in FIG. 10 differs from theembodiment according to FIG. 9 in that a four-links system FS4 designedas a parallelogram is present instead of a link arm 21 q (see FIG. 9)connected to the rotor of the rotary means 19 q so as to be securedagainst relative rotation thereto. The rotor of the rotary means 19 r isconnected to one of the links 148, 150, namely the one denoted 148, inFS4.

The four-links system FS4 is coupled to the link system 23 r at its endturned away from the rotary means 19 r. The links 148 and 150 aremovable relative to the carrier 110 with one degree of freedom, namelypivoting about parallel axes. The carrier 110 may be said to form a linkin FS4. The remaining link 152 thereof is connected to one of the linksin the link arm arrangement 23 r.

Thus, the rotary means 19 r is capable of causing the four-links systemFS4 to pivot.

It is pointed out that the solution with an axle and an arm 21 qaccording to FIG. 9, i.e. without parallelogram, also may be obtainedwith a stationary rotor of 19 r and an angular gear 112. 113.

FIG. 11 illustrates an embodiment reminding about the one in FIGS. 9 and10 in the sense that also here the movement arrangement 6 s is realisedas a pivot arm 100 s. The link arrangement 5 s has its links hingedlyconnected with one of the its ends to the base-like first element 1 s.The second end of the links in the link arrangement 5 s are hingedlyconnected to a connection arrangement 4 s. The links in the linkarrangement 5 s are pivotable in all directions relative to the firstelement 1 s as well as the connection arrangement 4 s. The pivot arm 100s is pivotably connected to the connection arrangement 4 s about an axledenoted 149. This axle may have an arbitrary direction relative to thelongitudinal extent of the links contained in the link arrangement 5 s.As is the case, which will be described later, according to FIGS. 12 and13, a force-applying arrangement 33 s acts upon the pivot arm 100 s viaa link arm arrangement 106 s, 107 s of a similar nature as the one inthe embodiment according to FIGS. 12 and 13. A working member 3 s may bearranged at that end of the pivot arm 100 s which is remote form theconnection arrangement 4 s.

FIG. 12 illustrates an embodiment where the movement arrangement 6 t isarranged between the connection arrangement 4 t and the second 2 t ofthe elements. The first link arrangement 5 t is provided between theconnection arrangement 4 t and the first 1 t of the elements. The second2 t of the elements is formed by or intended to carry a working member 3t. The movement arrangement 6 t is formed by an arm pivotable relativeto the connection arrangement 4 t. The links 9 t of the first four-linkssystem FS1 are pivotable in all directions relative to the first element1 t and the connection arrangement 4 t for the following reason: Aforce-applying arrangement 18 t has a movable portion connected to thelinks 9 t via the link 43 t so that FS1 may be pivoted in the XY-plane.The power-exerting arrangement 19 t has a stationary portion rigidlyconnected to a movable portion 21 t of the further force-applyingarrangement 18 t, which has a stationary portion secured relative to thefirst element 1 t. A link 43 t is rigidly connected to the movableportion 21 t of the force-applying arrangement 18 t and the stationaryportion of the force-applying arrangement 19 t. The arrangements 18 tand 19 t are suitably formed by rotary means. The links 9 t may now bepivoted in planes parallel to planes in which they reside themselves bymeans of the arrangement 19 t. By means of the arrangement 18 t, thelinks 9 t may be rotated about an axis at an angle, suitably a rightangle, to the just described pivot axis. Thus, the links 9 t may beoperated about two axes directed at an angle to each other. It ispointed out that the links 9 t have only one degree of freedom, i.e.pure pivoting, relative to the link 43 t, which together with the rotarymeans 19 t interconnects the links 9 t in the area of the pivot axis.Thus, the arrangement 19 t causing pivoting of the links 9 t will bemoved along by the arrangement 18 t on rotation thereof. The ends of thelinks 9 t turned away from the arrangements 18 t and 19 t are hingedlyconnected to a connection part 43 t via hinges 44 t having only onedegree of freedom, i.e. pivoting about a single axis. The connectionarrangement 4 t comprises a first element 10 t, which is pivotedrelative to the connection part 43 t with one degree of freedom, i.e.pure pivoting about the longitudinal direction of the connection part 43t, while forming a joint 104. The connection element 10 t is pivotedabout a further connection element 103 included in the connectionarrangement 4 t with one degree of freedom, i.e. a pure pivotingmovement about an axis parallel to the pivoting of the connectionelement 10 t about the connection part 43 t while forming a joint 105.The connection element 103 is connected to the first element 1 t via alink arm arrangement 14 t. This link arm arrangement 14 t comprises alink arm which is connected to the connection element 103 and the firstelement 1 t respectively via joints 15 t and 16 t respectively with atleast two degrees of freedom concerning pivotability. Thus, these joints15 t, 16 t should allow pivoting about two axes placed at an angle toeach other. A further degree of freedom in the form of rotation couldalso be allowed, in which case ball joints could be used for the joints15 t, 16 t in addition to cardan joints etc. It is suitable, althoughnot necessary, that the link arm 14 t forms a four-links system FS3 witheach of the links 9 t. It is preferred that the four-links system FS1and FS3 are given the form of parallelograms so that the orientation ofthe connection element 10 t always is maintained on pivoting of thelinks 9 t and 14 t.

The joints 44 t and 104 provide the links 9 t with pivotability in alldirections relative to the connection arrangement 4 t (its part 10 t).

In order to pivot the pivot arm 6 t relative to the connection element103 included in the connection arrangement 4 t, there is provided aforce-applying arrangement generally denoted 33 t. This comprises aforce-exerting member having a portion stationary relative to the firstelement 1 t and a movable portion having one degree of freedom relativeto the stationary portion. In the example an arm 106 is connected to themovable portion of the force-exerting member, said arm 106 beingconnected to the pivot arm 6 t via a link arm 107. The joints 108 and109 respectively of the link arm 107 relative to the arm 106 and thepivot arm 6 t comprise at least two degrees of freedom, namelypivotability about non-parallel axes, but may also be designed to allowrotation, i.e. have the character of ball joints.

The embodiment according to FIGS. 12 and 13 may be used so that thefour-links systems FS1 and FS3 may be pivoted in all directions relativeto the first element 1 t in order to vary the position of the connectionarrangement 4 t by operating the force-exerting arrangements 18 t and 18t. The pivot arm 6 t may be caused to pivot relative to the connectionarrangement 4 t so that the working member 3 t can be operated in spaceby operating the force-exerting arrangement 33 t.

As appears from FIG. 12, the second element 2 t can be said to form theextreme end of the pivot arm 6 t in this example. It would also bepossible to express oneself such that the second element 2 t is formedby the working member 3 t itself.

It is pointed out that in a variant, not illustrated, of the embodimentaccording to FIGS. 12 and 13, the angular gear solution shown in FIG. 10could be used in order to reduce means inertia.

FIG. 14 illustrates an embodiment suitable for achieving turning of theworking member 3 u starting from the first element 1 u so that anadequate turning position of the working member may be adjusted. Such anadjustment of turning position may be caused by various manipulativetasks to be carried out by the working member but is as a rule alsodesirable in that the pivoting embodiment of the robot means that theworking member 3 u on such pivoting will change its turning position inspace. It is illustrated in FIG. 14 that a power-exerting member 33 uhas a stationary portion secured to the first element 1 u and a movableportion connection to an arm 106 u. The pivot arm is denoted 6 u and thelink arm 107 u analogous to the previously described link arm having thesame numbering interconnects between the arm 106 u and the pivot arm 6u. By suitable driving of the force-exerting member 33 u the pivot arm 6u may be pivoted relative to the connection arrangement 4 u (notillustrated in FIG. 14) by intermediary of the arm 106 u and the linkarm 107 u.

On the first element 1 u there is a driving motor 114 for exertingenergy for turning the working member 3 u. The drive motor 114 has astationary portion connection to the element 1 u and movable portion,here in the form of a drive axle, adapted to put a drive wheel 115 inrotation. On the extreme end of the arm 106 u, a further wheel 116 isrotatably journalled and about these two wheels 115, 116 there is laid atraction force transmitting element 117 formed as a loop. The wheel 116is connected to an axle 118, on which a bevel gear wheel 119 is secured.The axle 118 is rotatable relative to the extreme end of the arm 106 u.About the axle 118 there is also journalled a support element 120, whichmay be moved about the axle 118 with one degree of freedom, i.e. purepivoting. This support member 120 is pivotably connected to an axle 121with one degree of freedom, said axle 121 also being rotatable relativeto the link arm 107 u. A bevel gear wheel 122 and a wheel 123 areconnected to the axle 121 so as to be secured against rotation relativethereto, a traction force transmitting element 124 formed as a loopbeing laid about the wheel 123, said element 124 also being laid about afurther wheel 125, which is rigidly connected to an axle 126 so as to besecured against relative rotation thereto, said axle 126 beingjournalled in the link arm 107 u at the extreme end thereof.

The gear wheels 119 and 122 form in unison an angular gear in that theaxles 118 and 121 extend substantially perpendicularly to each other.The axle 126 is rigidly connected to a bevel gear wheel 127, which is inengagement, while forming a further angular gear, with a bevel gearwheel 128 rigidly connected to the working member 3 u. The gear wheel128 is rigidly secured to an axle 129. This axle extends perpendicularlyto the axle 126. A further support element 130 is journalled relative tothe two axles 126 and 129 with one single degree of freedom, i.e. purepivoting.

The embodiment according to FIG. 14 operates in the following manner: Onactuation of the force-exerting member 33 u, the arm 106 u may bepivoted and the pivot arm 6 u be put in pivoting with intermediary ofthe link arm 170 u. The connections/force transmissions via the angulargears and the support elements 120 and 130 pivotably connected to thegear wheel axles means that there will occur possibility for movement intwo degrees of freedom, namely pivoting about two axes perpendicular toeach other, in the transition between on one hand the arm 106 u and thelink arm 107 u and on the other hand between the link arm 107 u and thepivot arm 6 u. This means that the arm 106 u pivotable in one plane iscapable of operating the pivot arm 6 u also when the latter is displacedaway from the pivoting plane of the arm 106 u as also is indicated inFIG. 14. On driving of the drive motor 114, the drive wheel 115 will beput into rotation. This drive wheel drives the traction forcetransmitting element 117 in the form of a belt, line, wire or chain sothat also the wheel 116 is put into rotation. The axle 121 is put inrotation via the angular gear 119/122 and this also causes rotation ofthe wheel 123, which will drive the wheel 125 via the element 124 suchthat the axle 126 is put into rotation. This will cause turning of theworking member 3 u via the angular gear 127/128.

FIG. 15 illustrates in principle a solution for achieving double forcetransmission between two parts of the device, said parts being pivotablerelative to each other about double non-parallel axes. Compared to theforce transmission between the arm 106 u and the link arm 107 uillustrated in FIG. 14, force transmission would be possible in doubleregard with assistance of the embodiment according to FIG. 15. Theexplanation thereto is that double sets of traction force transmittingelements 131, 132 are arranged in FIG. 15, said sets of elements beingdriven by separate drive motors and laid over a respective driven wheel133, 134. The axle 135 of the wheel 134 is designed as a tubular axlewhereas the axle 136 of the second wheel 133 protrudes through thetubular axle 135. The tube axle 135 is provided with a first bevel gearwheel 137 whereas the axle 136 is provided with a second bevel gearwheel 138 on its end having projected through the tube axle 135. Thegear wheel 137 connected to the tube axle 135 is in engagement with abevel gear wheel 139 arranged on a tube axle 140 while forming anangular gear. A wheel 141 is rigidly connected to the tube axle 140, thetraction force transmitting element 142 driven by the wheel 141 beinglaid over the same.

A further bevel gear wheel 143 engages with the gear wheel 138 and issecured to an axle 144, which projects through the tube axle 140 and isconnected to a wheel 145 driving a traction force transmitting element146, which runs further to a wheel (not illustrated) driven thereby, afact which also is valid for the element 142.

The transmission described in FIG. 15 allows, accordingly, a doubleforce transmission and at the same time a joint having two degrees offreedom, i.e. a joint allowing pivoting about two axes placed at anangle to each other. The transmission may be used in order to providethe associated robot structure with two degrees of freedom. Forinstance, the components 131, 133, 136, 138, 143, 144, 145 and 146 maybe used for turning the working member 3 whereas the other componentsare used for a different degree of freedom of the robot, e.g. movementof a part which in turns carries the working member.

FIG. 16 illustrates an alternative to the embodiment discussed withassistance of FIG. 14. Instead of force transmission by means of atraction force transmitting elements and wheels driving these elementsand being driven thereby respectively, axle transmissions 146, 147arranged along the arm 106 v and the link arm 107 v are used herein.This means that in the joint transitions further angular gear functionsmust be introduced as is immediately visible in the figure.

Common to all described embodiments is that a suitable control unit,particularly in the form of a computer, is arranged to control theforce-exerting members of the various robot embodiments for the purposeof causing the second element 2 or members coupled directly orindirectly thereto to move in intended paths.

It is pointed out that the expressions “force-exerting members” and“drive means” respectively should be interpreted in an extremelyextensive sense, unless otherwise is expressly stated. When thesemembers and means respectively are stated to comprise stators androtors, this includes that between said stators and rotors are coupledsuitable gears for the purpose of achieving a desired gear ratio.

POSSIBLE MODIFICATIONS

It is evident that the invention is not only limited to the embodimentsdiscussed above. Thus, detailed adaptations of the embodiments may becarried out depending upon the circumstances without leaving the scopeof the invention appearing from claim 1.

What is claimed is:
 1. A device for relative movement of two elements,comprising: a link arrangement; a movement arrangement coupled betweenthe link arrangement and a first element, wherein the link arrangementis coupled between the movement arrangement and a second element, saidsecond element being adapted and arranged to carry a working member, thelink arrangement having links pivotably connected via joints relative tothe movement arrangement and the second element, the movementarrangement being adapted to move relative to the first element, whereinthe movement arrangement is shaped as a pivot arm; first and secondforce-applying arrangements arranged to cooperatively move the secondelement relative to the pivot arm; and a third force-applyingarrangement which pivots the pivot arm relative to the first element,wherein the first, second, and third force-applying arrangements eachcomprise a respective first, second, and third force-applying memberwhich includes an associated rotating motor, wherein the associatedrotating motor for each of the second and third force-applying membershas a respective stator secured relative to the first element andaligned so that associated axes of rotation are aligned substantiallyparallel with each other.
 2. A device according to claim 1, wherein afirst set of links in the link arrangement, in conjunction with thepivot arm and the second element, form at least one first four-linkssystem.
 3. A device according to claim 2, wherein at least two of thefirst set of links comprise two traction force transmitting elementsarranged to maintain an orientation in space of the second element upona movement of the link arrangement.
 4. A device according to claim 3,wherein the two traction force transmitting elements are part of a looplaid about diverting members connected to the connection arrangement andto the second element belonging to the link arrangement respectively,the loop being fixed against displacement relative to the divertingmembers.
 5. A device according to claim 4, wherein the diverting membersinclude substantially arc-shaped diverting paths.
 6. A device accordingto claim 5, wherein a compression force transmitting first link hasopposite ends thereof located substantially centrally relative to thediverting paths.
 7. A device according to claim 1, wherein the firstforce-applying member is adapted and arranged to pivot with the pivotarm when the third force-applying member pivots the pivot arm.
 8. Adevice according to claim 1, wherein the first force-applying member hasan associated stator secured to the first element and an associatedrotor adapted and arranged to actuate the second element via an angulargear.
 9. A device according to claim 8, wherein a first gear of theangular gear is secured to the rotor of the first force-applying member,whereas a second gear of the angular gear is rotatably by a carrieradapted to be placed in rotation while the pivot arm is pivoting inresponse to the third force-applying member.
 10. A device according toclaim 1, wherein a transmission, driven by a drive motor on the firstelement which turns a working member on the second element, comprisesforce transmitting members extending along the link arrangement, theconnection arrangement, the movement arrangement and at least one otherlink arm arrangement of the device, said force transmitting memberscomprising axles and traction force transmitting elements laid arounddiverting wheels and angular gear members arranged between said axlesand said diverting wheels for force transmission without interferingwith a mobility of the device.
 11. A device according to claim 1,wherein double sets of traction force transmitting elements are laidabout diverting wheels which are rotatable about axles, said double setsof traction force transmitting elements being driven by separate drivemotors, wherein an axle of one of the diverting wheels is a tubularaxle, and an axle of a second diverting wheel projects through thetubular axle, wherein the axle of the one of the diverting wheels andthe tubular axle respectively are connected to respective angular gearwheels which, together with corresponding gear wheels of a further setof axles supporting rotatable diverting wheels for traction forcetransmitting elements, form a joint pivotable about double non-parallelaxles, the angular gear wheels engaging with each other and transmittinga force through an intermediate angular gear by said gear wheels.
 12. Adevice according to claim 1, wherein said device includes an industrialrobot, wherein the second element carries at least one working member.13. A device according to claim 1, wherein the second and thirdforce-applying members have respective rotors arranged with respectiveaxes of rotation.